The Hio clan was a family of Purebloods who date their origin back to the ancient vampires, much like the Kuran Family, and as such command great respect in Vampire society. Shizuka Hio, the only member of the family to appear in the story, tells how she was considered a "rare beast" and was locked and raised in a cage, for the sake of both humans and vampires, after being deemed uncontrollably violent by the Vampire Council, during which time she was given human sacrifices to feed her thirst for blood. If the entirety of the Hio family itself was extremely violent and went berserk and Shizuka was just one example of such tendencies is unclear, though proved unlikely by Shizuka referring to herself as a "rare beast". It seems that the rest of the Hio family were in sleep like the Hanadagi family, since in Volume 14 something Kaien said about Sara Shirabuki disturbing the Hio family.
Hi means scarlet and o means cherry blossoms.